/************************************************************************
                                                                     
   Xceed Ultimate ListBox for Silverlight                                                                                                                                            
   Copyright (C) 2010 Xceed Software Inc.    
                                                                     
   This program is provided to you under the terms of the GNU General Public  
   License version 2 as published by the Free Software Foundation. 
        
   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY, without even the implied warranty of 
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License along 
   with this program, if not, write to the Free Software Foundation, Inc., 
   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

   This program can be provided to you by Xceed Software Inc. under a
   proprietary commercial license agreement for use in non-Open Source
   projects. Visit Xceed.com to find the commercial edition of 
   Xceed Ultimate ListBox for Silverlight.                                    
                                                                      
 **********************************************************************/

using System;
using System.Text;

namespace Xceed.Silverlight.Data
{
  public abstract class FilterExpressionFormatter : FilterExpressionVisitor
  {
    #region Constructor

    protected FilterExpressionFormatter()
      : base()
    {
    }

    protected FilterExpressionFormatter( FilterExpressionBase expression )
      : base( expression )
    {
    }

    #endregion

    #region PartialResult Protected Property

    protected StringBuilder PartialResult
    {
      get
      {
        return m_partialResult;
      }
    }

    private StringBuilder m_partialResult = new StringBuilder();

    #endregion

    protected override void Initialize()
    {
      m_partialResult.Clear();

      base.Initialize();
    }

    protected virtual string GetFormat()
    {
      // This is the format that will be use for every expression of 
      // type FilterExpressionBase.
      return "({0})";
    }

    protected virtual string GetFormat( FilterExpression expression )
    {
      // {0}: Property name
      // {1}: Filter operator
      // {2}: Value
      switch( expression.FilterOperator )
      {
        case FilterOperator.StartsWith:
        case FilterOperator.EndsWith:
        case FilterOperator.Contains:
        case FilterOperator.ContainedIn:
          return "{0}.{1}( {2} )";

        default:
          break;
      }

      return "{0} {1} {2}";
    }

    protected virtual string GetFormat( AndFilterExpression expression )
    {
      return FilterExpressionFormatter.GetFormat( expression, "And" );
    }

    protected virtual string GetFormat( OrFilterExpression expression )
    {
      return FilterExpressionFormatter.GetFormat( expression, "Or" );
    }

    protected virtual string GetFormat( NotFilterExpression expression )
    {
      return "Not {0}";
    }

    protected virtual string GetMemberName( FilterExpression expression )
    {
      return string.Format( "{{{0}}}", expression.MemberName );
    }

    protected virtual string GetFilterOperator( FilterExpression expression )
    {
      switch( expression.FilterOperator )
      {
        case FilterOperator.Equal:
          return "==";

        case FilterOperator.NotEqual:
          return "!=";

        case FilterOperator.GreaterThan:
          return ">";

        case FilterOperator.GreaterThanOrEqual:
          return ">=";

        case FilterOperator.LessThan:
          return "<";

        case FilterOperator.LessThanOrEqual:
          return "<=";

        case FilterOperator.StartsWith:
          return "StartsWith";

        case FilterOperator.EndsWith:
          return "EndsWith";

        case FilterOperator.Contains:
          return "Contains";

        case FilterOperator.ContainedIn:
          return "ContainedIn";

        default:
          return "?";
      }
    }

    protected virtual string GetValue( FilterExpression expression )
    {
      object value = expression.Value;

      if( value == null )
        return this.GetNullValue();

      if( value is string )
        return string.Format( "'{0}'", value );

      if( value is DateTime )
        return string.Format( "#{0}#", value );

      return value.ToString();
    }

    protected virtual string GetNullValue()
    {
      return "#null#";
    }

    protected internal override void Visit( FilterExpression expression )
    {
      // Retrieve the string representation of each part of the filter expression.
      string memberName = this.GetMemberName( expression );
      string filterOperator = this.GetFilterOperator( expression );
      string value = this.GetValue( expression );

      string format = this.GetFormat( expression );
      string result = string.Format( format, memberName, filterOperator, value );

      this.AppendExpressionResult( result );
    }

    protected internal override void Visit( AndFilterExpression expression )
    {
      string format = this.GetFormat( expression );

      this.Visit( expression, format );
    }

    protected internal override void Visit( OrFilterExpression expression )
    {
      string format = this.GetFormat( expression );

      this.Visit( expression, format );
    }

    protected internal override void Visit( NotFilterExpression expression )
    {
      // Keep a copy of the partial result.
      string previousResult = this.FlushPartialResult();

      // Generate the content of the child expression.
      this.Visit( expression.ChildExpression );

      // Retrieve the content of the child expression.
      string childResult = this.FlushPartialResult();

      // Restore the original partial result.
      StringBuilder sb = this.PartialResult;
      sb.Append( previousResult );

      // Append the current expression to the partial result.
      string format = this.GetFormat( expression );
      string result = string.Format( format, childResult );

      this.AppendExpressionResult( result );
    }

    private void Visit( FilterExpressionOperator expression, string format )
    {
      int childCount = expression.ChildExpressions.Count;
      string[] childResults = new string[ childCount ];

      // Keep a copy of the partial result.
      string previousResult = this.FlushPartialResult();

      for( int i = 0; i < childCount; i++ )
      {
        // Generate the content of the child expression.
        this.Visit( expression.ChildExpressions[ i ] );

        // Retrieve the content of the child expression.
        childResults[ i ] = this.FlushPartialResult();
      }

      // Restore the original partial result.
      StringBuilder sb = this.PartialResult;
      sb.Append( previousResult );

      // Append the current expression to the partial result.
      string result = string.Format( format, childResults );

      this.AppendExpressionResult( result );
    }

    private string FlushPartialResult()
    {
      StringBuilder sb = this.PartialResult;
      string partialResult = sb.ToString();
      sb.Clear();

      return partialResult;
    }

    private void AppendExpressionResult( string result )
    {
      string format = this.GetFormat();

      this.PartialResult.AppendFormat( format, result );
    }

    private static string GetFormat( FilterExpressionOperator expression, string operatorGlyph )
    {
      StringBuilder sb = new StringBuilder();
      int count = expression.ChildExpressions.Count;

      for( int i = 0; i < count; i++ )
      {
        if( i > 0 )
        {
          sb.Append( " " ).Append( operatorGlyph ).Append( " " );
        }

        sb.Append( "{" ).Append( i ).Append( "}" );
      }

      return sb.ToString();
    }
  }
}
